Method for the preparation of phosphate esters



United States Patent 3,346,670 METHOD FOR THE PREPARATION OF PHOSPHATEESTERS John G. Papalos, Fort Worth, Tex., assignor to General Aniline &Film Corporation, New York, N.Y., a corporation of Delaware No Drawing.Filed Dec. 11, 1962, Ser. No. 243,721 11 Claims. (Cl. 260980) Thisinvention relates to the preparation of organic phosphorus-bearingcompounds and relates more particularly to an improved process forpreparing phosphate-free acid esters of nonionic surface active agents.

The particular nonionics of interest in the process of the instantinvention are the nonionic surface active agents having the molecularconfiguration of a condensation product of at least one mole of analkylene oxide with one mole of a compound containing at least 6 carbonatoms and a reactive hydrogen atom are preferably polyoxyalkylenederivatives of alkylated and polyalkylated phenols, multi-branched chainprimary aliphatic alcohols having the molecular configuration of analcohol produced by the oxo process from a polyolefin of at least 7carbon atoms, and straight chain aliphatic alcohols of at least carbonatoms. The alkylene oxide may be propylene oxide, butylene oxide orpreferably ethylene oxide. Examples of these derivatives and othersuitable nonionic surface active agents which may be phosphated inaccordance with the present invention are included below. In this list,E.O. means ethylene oxide and the number preceding same refers to thenumber of moles thereof reacted with one mole of the given reactivehydrogen containing compound.

Nonylphenol-i-9-11 E.O. Nonylphenol+2 E.O. Dinonylphenol+7 E.O.Dodecylphenol+18 E.O. Castor 0il|20 E.O. Tall oil+18 E.O. Oleylalcohol+20 E.O. Lauryl alcohol +4 E.O. Lauryl alcohol+ E.O. Hexadecylalcohol+ 12 ED. Hexadecyl alcohol+ E.O. Octadecyl alcohol+20 E.O. Oxotridecyl alcohol:

(From tetrapropylene) +7 E.O. (From tetrapropylene) +10 E.O. (Fromtetrapropylene) +15 E.O. Dodecyl mercaptan+9 E.O. Soya bean oil amine+10E.O. Rosin amine+32 E.O. Coconut fatty acid amine+7 E.O. Cocoa fattyacid+10 E.O. Dodecylbenzene sulfonamide+10 E.O. Decyl sulfonamide-i-GE.O. Oleic acid-i-S E.O. Polypropylene glycol (30 oxypropylene units)+10E.O.

It can be seen from the above exemplary nonionics that the optimumstarting materials are those selected from the group consisting ofphenol, alkyl phenols, alphatic alcohols, fatty acids, fatty amines,fatty amides, rosin amines, long chain sulfonamides, longchain-substituted aryl sulfonamides, and high molecular weightmercaptans.

Nonionic surface active agents such as those of the instant inventionhave been previously esterified with a number of different phosphatingagents, including phosphorus trichloride, PCl phosphorus oxychloride,P001 and phosphorus pentoxide, P 0 Esters produced from thechlorine-containing phosphating agents, such as the phosphorustrichloride and the phosphorus oxychloride, contain bound chlorine atomswhich are undesirable in many applications. The perferred phosphatingagent used in most instances heretofore has been phosphorus pentoxide.However, the product yield of phosphate esters resulting from theconventional phosphation reactions employed heretofore, with phosphoruspentoxide as a phosphating agent, has been relatively poor, especiallywith the higher molecular weight nonionic surface active agents. As muchas of the organic starting material has failed to be converted to itsrespective phosphate esters with the prior art processes.

It is an object of the instant invention to provide a process for thepreparation of phosphate esters from nonionic surface active agents freefrom the foregoing and other disadvantages.

A further object of this invention is the provision of a process for thepreparation of phosphate esters of nonionic surface active agentswherein a much higher percentage of the organic starting materials willbe converted to phosphate esters.

Other objects and advantages of the instant invention will appear fromthe following detailed description and the appended claims.

Nonionic surface active agents such as those of the instant inventionhave been converted heretofore to their phosphate esters by firstazeotropically distilling the compounds to remove all traces of waterand then reacting the dried compound with phosphorus pentoxide underanhydrous conditions. The removal of water prior to the phosphationprocess has been considered necessary to prevent the formation ofphosphoric acid by reaction of the water with the phosphorus pentoxide.The presence of phosphoric acid during the phosphation reaction haspreviously been believed to be disadvantageous to a satisfactoryphosphation. While it has been recently discovered that phosphation inthe presence of certain phosphorus-containing compounds, such ashypophosphorous acid and salts thereof, and phosphorous acid and saltsand esters thereof, will improve the color of the reaction products, thepresence of water or phosphoric acid has been carefully avoided.

It has now been unexpectedly discovered that the introduction of smallquantities of water into the nonionic surface active agents prior toreacting the same with phosphorus pentoxide will produce a reactionproduct containing much higher concentrations of phosphate esters thanthe products of prior art processes. While it has been recognizedpreviously that the presence of Water in the nonionic surface activeagents affects the ratio of the products and by-products in the reactionmixture, it has not been realized heretofore that incorporation of Waterwill greatly increase the conversion of the nonionic sur-.

face active agents to its phosphate esters.

As previously mentioned, it is believed that water pres cut during thephosphation reaction reacts with the phosphorus pentoxide to formphosphoric acid. It is hypothesized that the acid formed by the additionof water prior to phosphation, in accordance with the process of theinstant invention, catalyzes the phosphation reaction and produces anincreased yield of phosphate esters. This hypothesis was substantiatedby adding small amounts of mineral acids, such as phosphoric, sulfuric,hydrochloric, boric, bromic, hydrobromic, hypobromous, hypophosphoric,metaphosphoric and pyrophosphoric acids and the like to the nonionicsurface active agents in lieu of the water. It was found that theaddition of these acids produced an increase in the conversion of thenonionic surface active agents to its phosphate ester comparable to thehigher yield produced by the addition of Water. It can therefore be seenthat it has been surprisingly discovered that addition of either wateror a mineral acid to the nonionic surface active agents prior to thephosphation process, as set forth hereinabove, will result in anincreased conversion to the phosphate ester. The invention is not to berestricted to the particular method by which the mineral acid isintroduced into the nonionic surface active agents. The preferredmineral acids are phosphoric, sulfuric and hydrochloric. However, thepreferred embodiment of the instant invention is the addition of waterrather than a mineral acid to the dried nonionic surface active agents,since the former additive is obviously more economical and avoids thenecessity of incorporating acids which are foreign to the reactionmixture.

Increased conversion has been realized by adding from 0.001 to 3% byweight of water or mineral acid, based on the weight of the driednonionic surface active agents. The preferred percentage of additive,however, is between 0.1 and 0.8%

The reaction products of the process of the instant invention arebelieved to be a mixture of the orthophosphates and pyrophosphates ofthe nonionic surface active agents starting materials. Phosphate estersof various nonionic surface active agents have found numerous commercialapplications such as detergents, lubricants, oil additives, antistaticagents, foaming agents, corrosion inhibitors and the like. Moreover,many of the phosphate esters have shown multiple applications when theycontain higher concentration of phosphates. The importance of thediscovery of the instant invention which makes possible the productionof such high concentration phosphate products is readily seen.

Good conversion to the phosphate esters has been especially difiicultheretofore with the higher molecular weight nonionic surface activeagents. That is, the phos phate esters of the higher homologues of thenonionic surface active agents used in the instant invention have beenconsidered more diflicult to prepare using prior art techniques. Theincreased conversion produced by the addition of small amounts of water,in accordance with the preferred mode of this invention, is thereforeespecially important commercially in this instance, since many of thephosphate esters of the higher molecular weight nonionic surface activeagents are desired in the various applications set forth hereinabove.

An additional advantage realized by adding small amounts of water to thedried nonionic surface active agent prior to treatment "with phosphoruspentoxide is that previous attempts to use higher percentages of thisphosphating agent to increase the yield of phosphate esters have notbeen successful. It has been discovered that the conversion has not beenincreased heretofore by a higher concentration of the phosphoruspentoxide because this phosphating agent has formed lumps when added inexcess to the dried nonionic surface active agent. The addition of smallamounts of water prior to phosphation has been found to eliminate thisphenomenon of lumping. The prior art phosphation processes have reactedone mole of phosphorus pentoxide with from 2 to 4.5 moles of thenonionic surface active agent. It is now found that a ratio of from 1 to3 moles of phosphorus pentoxide to Example 1 Procedure A.Into a twoliter, electrically heated, reaction flask, fitted with an agitator, athermometer,.and a water separator fitted to a reflux condenser, ischarged 600 parts of nonylphenol containing fifteen moles of ethyleneoxide (0.682 moles of the nonionic surface active agents) and 200 partsof xylene. The mixture is heated to reflux until water is completelyremoved from the reaction mixture. The xylene is then removed bydistillation and the dried nonionic surface active agents are cooled to50 C. The apparatus is then re-arranged so that inert gas is bubbledthrough the reaction mixture and a vent is kept open. While using anagitator speed of 400 revolutions per minute, 150 parts (0.358 moles) ofphosphorus pentoxide is added over a period of one and one-half hours.The temperature of the reaction mixture is maintained at 70-95 C. duringthis period. The reaction mixture is then heated to 120130 C for fivehours. This mixture is then cooled to 90 C. and discharged. The finalproduct is analyzed by means of a conventional ion exchange procedure.There is found to be 9.38 percent of unreacted nonionic surface activeagent.

Procedure E.The same charge and procedure as in A above is employed,except that after the water is removed, there is added 2.5 parts ofwater to the dried nonionic surface active agents. Analysis of theproduct by an ion exchange procedure showed 2.34 percent of unreactednonionic surface active agents.

Procedure C.-Procedure A is repeated except, after the water is removed,there is added 3 parts of phosphoric acid to the dried nonionic surfaceactive agents. The unreacted nonionic surface active agents of theresulting product is 1.15 percent.

Procedure D.Procedure A is repeated except, after the water is removed,there is added 3 parts of hydrochloric acid (chemically pure) to thedried nonionic surface active agents. The unreacted nonionic surfaceactive agent in the phosphated product is 3.0 percent.

Procedure E.Procedure A is repeated except, after the water is removed,there is added 4.8 parts of sulfuric acid (chemically pure). Theresulting product is found to contain 2.5 percent of unreacted nonionicsurface active agent.

Procedure F.Procedure A is repeated except, after the water is removed,there is added 4.8 parts of water to the dried nonionic surface activeagent. There is found 2.0 percent of unreacted nonionic surface activeagent in the resulting product.

Procedure G.Procedure A is repeated except, after the water is removed,there is added 0.6 part of water to the dried nonionic surface activeagent. There is found 2.5 percent of unreacted nonionic surface activeagent in the resulting product.

As seen from the above example, the Procedures B, C, D, E, F, and Gyielded comparable results. This evidences the fact that the improvedconversion is catalyzed by the presence of a mineral acid which can beadded directly to the dried nonionic surface active agent or formed bythe addition of water. It is also readily seen from the above resultsthat even trace amounts of additives provide substantially increasedconversion to the phosphate ester.

The reaction temperature is not limited to 120130 C. as shown inProcedure A but can be as high as 200 C. The pressure may beatmospheric, subatmospheric or superatmospheric. The only limitation onthe reaction conditions is that the temperature and pressure are'suchthat the added water or mineral acid is not driven olf during thereaction.

The following table lists the pertinent data on several phosphate estersprepared by our preferred Procedure B 1 water is added in an amountbetween 0.1 and 0.8 percent based on the weight of said nonionic surfaceactive agent. 5. A process for the preparation of phosphate esterscomprising reacting one mole of phosphorus pentoxide and compares themwith products prepared according with 0.3 to 2 moles of a nonionicsurface active agent to Procedure A as a control.

having the molecular configuration of a condensation Percent PercentMolar Ratio Parts by Unreacted Unreacted of Nonionic Weight of ExampleM.W. Structural Formula of Nonionic Nonlonic Noniom'c Surface NomomcSurface Active Agent Surface Agent Surface Agent Active Agents SurfaceActive Agent by Agent by to P Agents to Procedure A Procedure B Parts ofP20 2, 420 O9H19CBH4 OC2H4 5ILOH 44. 7 12. 9 1:3 5. 7:1 1, 498C6H13C6H4(OC2H4)30-OH 25. 2 4. 6 1:3 3. 5:1 C36H73C6H4(0CH 18. 5 6. 31:2 4. 5:1 30.0 5.0 1.5:1 10:1 35.0 6.8 1.511 13:1 20.0 4.5 1.99:1 12:193.0 84.2 121.5 32:1 5.2 1.7 1.921 8.921 8.4 1.3 L911 14:1 6.3 2.0 1.9:112:1 11.2 1.2 1.921 18:1 75.5 30.0 1:3 9.621 95.1 50.2 1:3 16:1 3.6 1.61.911 8.221 15.4 5.9 1:1 11.5:1 3.5 1.2 1.921 7.7:1 CsH|o(OC2H )-2o.OH26.0 6. 0 1.5:1 10:1 1, 918 (C1BH37)2C6H3(OC2H4)30 H 12. 1 7. 3 121 13.5:1 1, 236 CgzH45(OC2I'I-|)zu-0H 19. 4 6. 2 1: 1 8. 7:1

The increase in conversion by the incorporation of water prior tophosphation is clearly seen from the above table. It will be noted thatextremely high percentages of unreacted nonionic surface active agentwere present in the reaction products of the higher molecular weightnonionic surface active agents produced according to Procedure A,especially those having a molecular weight in excess of 2,000, and thatsubstantially improved conversion resulted in most instances from theuse of Procedure B. It is also of special interest that the molar ratioof the nonionic surface active agent to the phosphorus pentoxide is fromone to two moles of nonionic surface active agent to from one to threemoles of pentoxide, a ratio heretofore believed disadvantageous. N

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of this invention.

What is hereby claimed and desired to be secured by Letters Patent is: I

1. A process for the preparation of phosphate esters comprising reactingphosphorus pentoxide with ethoxylated nonyl phenol or an ethoxylatedaliphatic alcohol containing at least 6 carbon atoms, wherein a smallamount of water is added to said ethoxylated nonyl phenol or aliphaticalcohol prior to the reaction with phosphorus pentoxide.

2. A process for the preparation of phosphate esters comprising reactingone mole of phosphorus pentoxide with 0.3 to 2 moles of a nonionicsurface active agent having the molecular configuration of acondensation product of at least one mole of alkylene oxide and one moleof a compound containing at least 6 carbon atoms and a reactive hydrogenatom, and selected from the group consisting of phenol, alkyl phenols,aliphatic alcohols, fatty acids, fatty amines, fatty amides, rosinamines, long chain sulfonamides, long chain-substituted arylsulfonamides, and high molecular weight mercaptans, wherein .001% to 3%by weight of water is added to said nonproduct of at least one mole ofalkylene oxide and one mole of a compound containing at least 6 carbonatoms and a reactive hydrogen atom, and selected from the groupconsisting of phenol, alkyl phenols, aliphatic alcohols, fatty acids,fatty amines, fatty amides, rosin amines, long chain sulfonamides, longchain-substituted aryl sulfonamides, and high molecular weightmercaptans, wherein .001% to 3% by weight of a material selected fromthe group consisting of Water and a mineral acid selected from the groupconsisting of phosphoric, sulfuric, hydrochloric, boric, bromic,hydrobromic, hypobromous, hypophosphoric, metaphosphoric andpyrophosphoric acids is added to said nonionic surface active agentprior to the reaction with phosphorus pentoxide.

6. A process in accordance with claim 5, wherein said alkylene oxide isethylene oxide.

7. A process in accordance with claim 5, wherein said material is addedin an amount between 0.1 and 0.8 percent based on the weight of saidnonionic surface active agent.

8. A process for the preparation of phosphate esters comprisingazeotropically distilling a nonionic surface active agent having themolecular configuration of a condensation product of at least one moleof alkylene oxide and one mole of a compound containing at least 6carbon atoms and a reactive hydrogen atom and selected from the groupconsisting of phenol, alkyl phenols, aliphatic alcohols, fatty acids,fatty amines, fatty amides, rosin amines, long chain sulfonamides, longchain-substituted aryl sulfonamides, and high molecular weightmercaptans, to remove any water present therein, drying said nonionicsurface active agent, adding to the dried nonionic surface active agent.001% to 3% by weight of water and then reacting 0.3 to 2 moles of saidnonionic surface active agent with one mole of phosphorus pentoxide.

9. A process in accordance with claim 8, wherein said nonionic surfaceactive agent is a nonylphenol containing fifteen moles of ethyleneoxide.

10. A process in accordance with claim 8, wherein said water is added inan amount between 0.1 and 0.8 percent based on the Weight of saidnonionic surface active agent.

11. A process in accordance with claim 8, wherein said nonionic surfaceactive agent has a molecular weight in excess of 2,000.

References Cited UNITED STATES PATENTS 2,853,471 9/1958 Beadell 260-980X 3,004,056 10/1961 Nunn et a1. 260-980 X Nunn 260980 Clarke et a1260-980 X Chiddix et a1 260980 X Sorstokke et a1. 260-974 5 CHARLES B.PARKER, Primary Examiner.

I. MARCUS, Examiner.

F. M. SIKORA, R. L. RAYMOND, Assistant Examiners.

1. A PROCESS FOR THE PREPARATION OF PHOSPHATE ESTERS COMPRISING REACTINGPHOSPHORUS PENTOXIDE WITH ETHOXYLATED NONYL PHENOL OR AN ETHOXYLATEDALIPHATIC ALCOHOL CONTAINING AT LEAST 6 CARBON ATOMS, WHEREIN A SMALLAMOUNT OF WATER IS ADDED TO SAID ETHOXYLATED NONYL PHENOL OR ALIPHATICALCOHOL PRIOR TO THE REACTION WITH PHOSPHORUS PENTOXIDE.